The present invention relates to management of a multi-tier storage environment, and more specifically, this invention relates to efficient management of high performance tiers in a multi-tier storage environment.
A file system defines how files are named and manages how they are placed for storage and retrieval. File system functionality may be divided into two components: a user component and a storage component. The user component is responsible for managing files within directories, file path traversals, and user access to files. The storage component of the file system determines how files are stored physically on the storage device.
A file system snapshot is a common industry term denoting the ability to record the data of a storage device or file system at any given moment. A snapshot primarily creates a point-in-time copy of data. Typically, a snapshot copy is performed instantly and made available for use by other applications, such as data protection, data analysis and reporting, and data replication applications, among others. The original copy of the data continues to be available to the applications without interruption, while the snapshot copy is used to perform other functions on the data. Snapshot copies enable better application availability, faster recovery, easier back up management of large volumes of data, reduces exposure to data loss, virtually eliminates the need for backup windows, and lowers total cost of ownership (TCO).
Copy-On-Write (COW) follows a simple principle: as long as multiple programs need read-only access to a data structure, providing these programs with pointers which point to the same data structure, instead of copying the whole structure to a new data structure, is sufficient to satisfy these programs needs. If at least one of the programs needs, at some point in the future, write access to the data structure, then a private copy may be created for it. When using a COW-based file system, offering snapshot support is straight-forward.